Telegraph signal formulating mechanism



Nv 17, 1942 s. H. aREEDLov; 2,302,290

TELEGRAPH SIGNAL yFORMULATIHG MECHANISM Filed Feb. 29, 1940 Dor l/Nir.

:1:1 u 30 Da Shes Dois Patented Nov. 17, 1942 UNITED sTATEs TELEGRAPH SIGNAL FORMULATING MECHANISM Bernard H. Breedlove, Boston, Mass.

Application February 29, 1940, Serial No. 321,506

8 Claims.

-the signals formulated thereby are subject to variation and irregularity of length and spacing, which may make them diflicult to interpret, due

to the fatigue and personal operating characteristics of the operator.

As a result of the objections of the verticalaction key a double-contact side-action key is largely used, wherein a vibratory pendulum, set

in motion by the sidewise movement of the key, f

makes and breaks the signal circuit to produce the dots of the code, and the arrangement being such that moving the key into one position and holding it in that position causes a series of dots to be transmitted, while moving the key into the z:

opposite position causes the circuit to be closed so that a dash can be made foreach closure.

This type of key is considerably less fatiguing to operate than a vetrical-action key, since it does not have to be vibrated for each dot. Itis, however, open to a number of objections. The number of dots it will send with one key movement is strictly limited. The amplitude of vibration of the signal pendulum continuously diminishes from the initial impulse so that rather careful adjustments are necessary to secure uniform repeated signals, as a string of dots. The greatest objection, however, is that the operation of the signal pendulum is detrimentally inuenced by the motion and vibrationof the sup- E port. Thus on shipboard, and particularly on a small vessel, and on airplanes, pitch and roll of the craft and the vibration of the engine can cause this type of key to fail to transmit the intended signal.

Hence an object of the present invention is the provision of means to form the dots and preferably also the dashes that constitute a telegraph code, which means is uniniluenced by movement or vibration of the support.

Another object of the invention is the provision of signal formulating means wherein an indefinite string of signals can be transmitted and wherein the character of the signals, that is, the length of the signal impulse, and the CII interval between successive impulses of the same order is determined by the constants and characteristics of an electric circuit, rather than by mechanical timing apparatus.

A yet further object of the invention is the provision of timing circuits for the initiation of a series of dot and dash forming impulses with a key for selecting the desired circuits and initiating their operation.

An additional object of the invention is the provision of a timing circuit arranged to be actuated to initiate its series of signal impulses upon the instant of its selection for service.

Another object is generally to improve the construction and operation of code signal transmitters.

Fig. 1 is a diagrammatic View of a code signal transmitter embodying the present invention.

Fig. 2 is a modication of the transmitter of Fig. 1 wherein the dash-signal unit is replaced by key-meansto form the dashes.

Fig. 3 is Aa-view illustrating a modied form Itrated, the circuit having the usual key I2 therein, o-r no key.

In that form of the invention illustrated in Fig. 1, two signal formulating circuit units A and B are employed, the A. unit forming the dots and the B unit forming the dashes. The circuits are or can be identical except for the electrical characteristics of the parts thereof.

The selection and energization of the units is under control of a double-contact side-action key I4, the movable blade or arm I 6 of which normally occupies a mid-position between and free from contactwith stationary side contacts I8 and 20. When the keyA is moved to the right into engagement with contact I8 the dot unit is selected and energized to transmit an indenite succession of short current pulses or dots terminated only by vbreaking the contact i8. The contact Ztl similarly selects and controls the operation of the dash unit B.

The dot unit A includes a three-element thermionic or space-conduction tube 22 having the anode or plate 2li, the control element or grid 2B, and thecathode or iilament 28. The plate circuit includes the energizingwinding orv coil 30 of a relay 32 which is in series between the plate and the contact I8 of the key I4. The movable blade or bar I6 of the key is connected to the positive terminal of the plate power source or battery 34, the negative terminal of which is connected to the cathode. Thus when the key is displaced to the right and the tube is conditioned to pass a suitable amount of plate current, the relay winding is effectively energized. The Winding, When e'ectively energized, moves two mutually insulated contact arms 36 and 38 to the left into engagement with front contacts 40 and 42 and moves the arm 38 away from engagement with the back contact 44. The arm 36 and contact 40, when engaged, close an output circuit 45 which is connected with the signal circuit I across the terminals of the signal circuit key I2 so that the result is the same as the closing of said key. The thermionic tube and its control circuits are arranged to energize and deenergize the relay 32 in rapid succession to form a series of dot-impulses in the signal circuit.

For this purpose the plate circuit of the tube is made periodically conducting and non-conducting by means including a capacity or condenser 48, and resistors U and 52, both of which preferably are variable. The condenser 48 is in shunt with the shunt grid circuit 54 and also in series with a grid biasing battery 56 or other source of potential, the function of which is to make the grid suciently negative, when the condenser 48 is suilciently discharged, to render the plate circuit sufficiently non-conducting to effectively de-energize the relay winding 30 and permit the movable contacts to fall back under urge of gravity or the retractile spring 58.

The resistor 50 controls the time of charging the condenser and hence controls the time interval between successive dots. One end of the resistor is connected to the positive terminal of the plate battery by a conductor 60 while the other end of the resistor is connected to the grid side of the condenser, between the condenser and the grid battery, through a conductor 62 and the serially-included relay contacts 38, 44. Thus When said contacts are engaged the condenser is connected across the plate battery and hence the potential of the initially discharged condenser ultimately rises to the potential of said battery after a time determined by the amount of current that the resistor 50 allows to ow and the capacity of the condenser. When the condenser is charged to full voltage, its positive potential is suiciently high to overcome the opposite potential of the grid biasing battery 54 and make the grid suciently positive to render the plate circuit sufliciently conducting to effectively energize the relay Winding 30, when the plate circuit through the key I4 is closed. Hence the relay operates and the output circuit 46 closes, thereby starting the transmission of the first dot.

The resistor 52 governs the duration of the dot and is placed in shunt with the condenser at the operation of the relay, by the engagement of the relay contacts 38, 42. The condenser thus discharges through said resistor at a rate dependent upon the resistance of the resistor. The resistor preferably is of adjustable resistance. Hence the voltage of the condenser, and of the grid, gradually drops and ultimately reduces the conductance of the plate circuit to a point where the plate current is -insuflicient to hold the relay closed, at which time the relay opens and the rst dot is terminated.

Upon the opening of the relay, the condenser is again connected with the plate battery through f the resistor 55. After a time delay dependent upon the resistance of the resistor, the plate circuit again becomes sufciently conducting to reenergize the relay, which closes and starts a second dot in the output circut. This action is repeated indenitely so long as the key I4 maintains the plate circuit closed. Upon opening the plate circuit, the relay opens and the transmission of dots ceases.

It will be seen that the first dot starts concurrently with the closing of the key circuit and that there is no time lag in obtaining control of the keying circuit I0.

The duration of the dot and the duration of the interval between successive dots can be made anything desired by suitably adjusting the resistance of the variable resistors 50, 52.

The dash unit B is similar to the dot unit as above described except that the capacity of the condenser 48D, corresponding to 48, and the resistance of the variable resistors 50h, 52h, corresponding to resistors 58, 52, are suitably different to provide longer duration of plate conductivity of the tube 22h so that the relay 32h is energized for a longer period of time to transmit dashes instead of dots. The relay 32h controls the output circuit 45 as does the relay 32, being connected in parallel with relay 32 in said circuit. The start of operation of the dash unit is controlled by moving the blade or bar I6 of key I4 to the left to engage contact 28 and thereby en ergize the plate and relay coil circuit, as described in connection with the dot unit.

With this arrangement it is merely necessary to hold the key to the left to send a series of dashes and to the right to transmit a series of dots.

In the modification illustrated in Fig. 2, the successive dots are made automatically while the successive dashes are made manually by successive movements of the key. In this modification, the dot-forming unit includes the tube 22, the condenser 48, the resistors `50, 52, the plate and grid batteries 34, 54, and the relay 32, all connected and arranged as in the dot unit A of Fig. 1 so that when the blade I6 of the key I4 is displaced to the right, the plate circuit is energized, as before, to close and open the output circuit 46 in a dot-forming manner. Thus the dots are made and transmitted automatically. The left hand contact 20a of the key, however, is connected by a conductor 64 to one end of a secondary winding 65 of the relay 32, the other end of which winding is connected to the negative side of the plate battery. Thus when the key is displaced to the left the secondary winding is energized and the relay actuated to close the output circuit, which circuit will remain closed so long as the key is held in its displaced position.

In the modification illustrated in Fig. 3, a negative resistance gaseous conduction element 'I0 comprising a neon tube having spaced electrodes 12, I4 in a neon atmosphere is utilized as the oscillation or pulsation controller. A condenser IB and a transformer 'I8 are connected in series between the electrodes. The secondary voltage of the transformer is amplied by a thermionic amplifier unit 88, the output circuit of which includes the winding 82 of a normally circuit-open relay 84 having contacts 86, 88 that when engaged close an output or signal circuit similar to the circuit 46, or IIJ. If the neon tube has suilicient current-passing ability the relay can be directly energized thereby, in place of 2,so2,29o

the transformer 18, and the latter and the amplier 80 can be omitted.

The neon tube is energized 'by a sufficiently high potential source 92 one end of which is connected to the tubeelectrode 14 and the other end offwhich is connected to the movable blade or bar 94 of a side action key 96. The key has side contacts 93 and |05) connected respectively with variable resistors |82, |64, the similar ends of which are both connected with the condenser 'i8 between it and the transformer 18.

As thus arranged, when the key is displaced on either side of its neutral position, the condenser is connected across the voltage source through either the resistor |02 or |04 and thus receives a charge at a rate dependent upon the resistance of the particular resistor. When the potential of the condenser is suciently high, this potential being impressed across the electrodes of the tube, the medium between the electrodes breaks down and the tube becomes conducting. The condenser thus discharges itself through the tube and transmits current through the transformer 18, and also a battery current which flows so long as the tube is conducting. Thus the relay 84 is energized. When the condenser is discharged the tube becomes non-conducting and the condenser again charges and the cycle is repeated so long as a key circuit is maintained closed. The resistance of the resistor |04 is so selected as to charge the condenser rapidly enough to form a series of dot impulses. The resistance of the re sistor |02 may be made sufficiently high, under suitable conditions, to charge the condenser at a slower rate thereby to form a series of dash impulses. However, by having the resistance of the resistor |02 suiciently less than that of resistor |04, so that the circuit oscillates at a sufliciently rapid rate to hold the armature 85 of the relay 84 in closed circuit position, as 'by a suitably weak adjustment of the retractile spring |05, the length of the dashes are then under manual control and the key must be separately engaged with the contact 98 for each dash.

I claim:

1. A telegraph code signalling system comprising an output circuit, a pair of impulse circuits each having space-conduction means for setting up successions of current impulses of dierent duration, a telegraph key. means responsive to movement of said key in different directions for energizing said impulse circuits selectively and for instantly initiating the primary impulse, and means responsive to said current impulses for controlling said output circuit.

2. A telegraph code signalling system comprising an output circuit, an impulse circuit having space-conduction means for setting up a succession of current pulses of determined duration, a relay having an energizing winding responsive to said pulses and having contacts controlling said output circuit, a telegraph key having contacts making and brealL'ng the circuit of said winding and controlling the operation of said relay, and other means under control of said key yfor impressing different signal pulsesron said output circuit.

3. A telegraph code signalling system comprising an output circuit, a signal-formulating circuit comprising a thermionic tube having cathode, control element and anode, means for impressing a biasing potential on said control element suicient in direction and amount to render the space path between said anode and cathode non-conducting, a condenser in the circuit of the mally maintaining a suicient control element, means for charging the condenser to a potential rendering the space path conducting and operative to maintain said path conducting in the idle condition of the system, resistors controlling the charge and discharge rates of the condenser, a relay having an energizing winding in the circuit of said anode, contacts controlled by said relay in its de-energized condition for connecting said charge resistor with said condenser to render the tube conducting and in its energized condition for connecting said discharge resistor to said condenser for rendering said tube non-conducting and thereby effecting periodic anodic current ow of predetermined duration, said relay in the condition corresponding to the de-energized condition of its winding maintaining said charge resistor connected with said condenser to condition the tube for conductivity, other contacts controlled by said relay controlling said output circuit, and a telegraph key controlling the anode current flow and amount of relay operations.

4. A telegraph code signalling system comprising a space conduction tube having means normally conditioning it for conduction, signal formulating means operative after a period of time following its operation to interrupt the conductivity condition of the tube and to periodically interrupt the conduction condition of the tube for periods of length comparable with the lengths of the spaces between telegraph signalling impulses and to restore conductivity for periods of lengths comparable with the lengths of the telegraph signalling impulses, means including a telegraph key controlling the operation of said signal formulating means, and signalling means responsive to the conductivity condition of the tube.

5. A telegraph signalling system comprising a thermionic tube having an anode, grid and cathode, means normally conditioning said tube for conductivity between anode and cathode, a telegraph key, and means responsive to the deflection of said key to reduce said conductivity after a predetermined period of time and to restore said conductivity after a predetermined period of time.

6. A telegraph signalling system comprising a thermionic tube having anode, grid and cathode, a timing condenser connected between cathode and grid, a charge circuit for said condenser having means controlling the rate of increase of potential across the condenser and of positive potential on the grid, a discharge circuit for said condenser having means for controlling the rate of decrease of grid positive potential and having associated therewith constantly operative grid biasing means for rendering the grid at times negatively biased, an anode circuit having a relay winding therein, contacts alternately controlling said charge and discharge circuits operated by the effective energization and de-energization of said Winding, and a telegraph key making and breaking said anode circuit and controlling the circuit of said winding.

7. A telegraph code signalling system comprising a thermionic tube having cathode, anode and grid, signal formulating means arranged when operative to render the tube periodically conducting and non-conducting and having means norpositive potential on said grid to render the tube operatively conducting, a telegraph key for making and breaking the anode current through the tube, and

` means operated by the anode current as controlled by said signal formulating means and by said key for controlling the operation of said signal formulating means and also for initiating signal impulses.

8. A telegraph code signalling system including a thermionic tube having cathode, anode and grid, means responsive to sufficient changes of anode current for periodically varying the grid potential to render the tube periodically operatively conducting and non-conducting including a source of potential independent of anode current, and means including a telegraph key for making and breaking the anode current.

BERNARD H. BREEDLOVE. 

